What is an Expert Witness?

The senior subject matter specialists at Water Treatment Services are experienced expert witnesses, providing independent, impartial and reliable advice on a range of engineering and environmental disputes involving the use, analysis and treatment of water, wastewater, trade effluent and air quality. Our specialists are often asked what is an expert witness, what do they do and how can they help avoid or resolve disputes?

This short guide has been prepared to explain the role of the expert witness, who can be one, what they do and don’t do, the processes involved in appointing one, and the different types of expert witness and what they involve.

If you’re a fan of legal dramas, you’ll perhaps be familiar with the role of the expert witness. This is the person who has the job of looking at the evidence in a court case or trial, and giving an independent opinion to help resolve the matter more quickly. Expert witnesses might appear in civil and criminal court cases, tribunals or arbitrations.

In the strict legal definition, there are two separate types of expert witnesses. These are:

Report But No Opinion
Witnesses who can help explain complex evidence to the jury or court but who will not give opinion.
Report Plus Opinion
Witnesses who will look at the evidence and give their own opinion about cause, or relevance to the case under consideration.

When to use an expert witness

Expert witnesses are used when their opinion is needed to provide the successful solution to a dispute. The idea is that using an expert will allow for a decision to be made more quickly. The expert is usually fully involved in the court proceedings, and might be called on to give evidence and be cross examined by the lawyers.

An expert witness has knowledge and experience of a subject that exceeds that of a layman.

Currently, courts are encouraging both sides in a dispute to agree on using a single joint expert (see below) to give a single opinion on a technical issue in court. This can help to streamline the process and also reduce costs.

After the expert has produced their report, both parties can then ask questions about anything contained in the report which they need further detail or clarification about, in order that everyone understands the issues and technical evidence in the case.

Who can be an expert witness?

Anyone whose knowledge or experience in a particular field could be called as an expert witness, assuming their knowledge and expertise goes beyond that of the average man in the street. Their job is to give an unbiased opinion to the court in matters which are open to interpretation or dispute. In most court systems, including that in England and Wales, the court has to give permission for an expert witness to be used.

What’s the difference between an expert witness and an expert advisor?

It’s important not to confuse the role of an expert witness with that of an expert advisor. The expert advisor works with one side or the other in a court case, and helps to prepare the case for the prosecution or defence case. This role might also involve explaining technical points or evaluating the strength of evidence, but it isn’t impartial.

Do you need an expert advisor?

What do expert witnesses do?

Expert witnesses can be called in a wide range of cases, but whatever the case under consideration, their duties are the same. The role of an independent witness will include:

Expert Opinion
Giving an expert opinion on their area of expertise, given the evidence in the case and the instructions given to them by the court. This opinion is written up in the expert witness’s report, which is shared with all parties involved in the case.
Expert Report
Making sure that their expert report covers everything which they have been asked for by the court. Expert reports are shared with the opposing side, but that also means your side will be able to look at their expert’s report too.
Unbiased & Independent
Give honest, unbiased and independent opinion on the facts in the case, whether or not this strengthens the case or not.
Duty to the Court
Bearing in mind that the duty of the expert witness is to the court, above any duty to the defence or prosecution team paying their wages.
Follow Set Procedures
Complying with whatever procedures or rules are in place for the tribunal or court they are appearing in.
Remain Independent
The court has the right to discount any report from an expert witness which appears to have been written to deliberately favour one side of the case or the other.

What an expert witness doesn’t do

Although there is plenty which an expert witness can do, there is lots which they can’t or won’t do in a court or a tribunal case. An expert witness will not, and cannot:

Take Sides
Argue your point of view or case to the judge or jury.
Additional Evidence
Go off to look for evidence to support your case.
Guidance
Make suggestions about what sort of evidence could be used to make your case stronger.
Beyond Expertise
Give opinion which is outside their direct area of expertise.
Advice
Give advice.
Conflict of Interest
Give expert witness testimony in any case which could be a conflict of interest.
Conditional Payments
Accept work when payment is conditional on the outcome of the case, such as in “no win no fee” personal injury cases. This payment structure doesn’t match with the idea of an independent expert.
Negotiate
Engage in negotiations with other parties on your behalf.

How to appoint an expert witness?

If you and your legal team agree that working with a particular expert witness would be beneficial to your case, then terms should be agreed in advance, and contracts signed. This should include details about what they will do and when, how much you are paying them, and how and at what stage they will be paid. There are model contracts online which can be downloaded and customised.

You should also give detailed instructions to your expert witness and keep them fully appraised of any developments in the case. Usually, it’s better for lawyers to deal with expert witnesses than members of the public.

Do you need an expert witness?

What are there different types of expert in England and Wales?

There are three types of expert witnesses used in the court system in England and Wales. Scotland and Northern Ireland have different legal systems and you should seek specific advice for court cases being heard there.

Party Appointed Expert
A party appointed expert witness is chosen and contracted to one of the sides involved in the dispute. It’s this person’s job to help the court on their topic of expertise. This overrides any duty the witness has to support the side which is paying their fees.
Single Joint Expert
A single joint expert is paid by both sides in a dispute and it’s their job to assist the court in understanding the facts of the case relative to their specific area of expertise.
Expert Advisor
An expert advisor doesn’t work for the court, but for one of the sides in the dispute. They generally do not give evidence or opinion in court; their role is to advise and guide the legal teams on matters involving their area of expertise.

Expert support for engineering and environmental disputes

Water Treatment Services provide independent, impartial and reliable advice on a range of engineering and environmental disputes involving the use, analysis and treatment of water, wastewater, trade effluent and air quality.

Our engineering and environmental specialists are highly sought after by the legal profession to act as expert witnesses or independent expert advisors to help avoid or resolve disputes.

Contact us today to learn how our expert witness and advisory solutions can help you avoid or resolve technical disputes.